Fuel



Patented Jan. 5, 193? UNITED STATES 2,066,506 PATENT OFFICE FUEL Cliiford A. Woodbury, Media, Pa.,

Lawson, Wilmington, du Pont de Nemours & Company,

and Walter E. Del., assignors to E. I. Wilmington,

Del., a corporation of Delaware No Drawing. Application October 13, 1932, Serial No. 637,670

4 Claims.

tion and the ignition of the fuel oil, a reduction in the ignition temperature of the fuel oil and/or a lowering of the compression ratio of the engine. A specific object relates to compression ignition fuels containing a nitrate of a polyhydric alcohol derivative, said derivative containing one or more solubilizing groups. A more specific object relates to compression ignition fuels containing as an ignition accelerator a polynitrate alkyl ester containing a solubilizing group. Other objects of the invention will become apparent from the following description.

' In accordance with the present invention, it has been found that when nitrates of polyhydric alcohols so modified as to render them soluble in the fuel oil are added to the fuel oil there is obtained a reduction in the delay period between injection and ignition of the fuel oil. This phenomenon is accomplished by a lowering of the ignition temperature of the fuel oil and/or a lowering of the compression ratio in the compression engine required to ignite the fuel. 1

The following table illustrates examples of nitrates of polyhydric alcohol derivatives containing solubilizing groups which may be used in accordance with the practice of the invention. This table also illustrates the effect of the use oi. these esters on the fuel'oil characteristics. The'properties of the doped or modified fuel oil are compared with those of unmodified fuel oil, the same quality of fuel oil being used in all of the examples.

Mini- Mini- Second mum ri Accelerator delay mum comat 514 proesio o. ratio Fueloil e94 vo was Fuel"t oil+5% by Prtgggalene glycol dini- 0.20 300- 0.4 Fuel oll+5% by 1, 3 butylene glycol o. 12 300 wt. dinitrate. Fuel oil+5% by Dimethyldimethylol- 0.12 300 8.8

It. methane dinitrate. r on-+691, by Dinitrochlorohydrim, o.17 3 9.2 radon-Fag, by Ethylencchlorohydrin 0.12 aoo wt. "nitrate. y Ffi nn+5%-b Monoethylindinitrate 0.11 215 The method of test for determining the ignition delay and minimum ignition temperature consisted in injecting the fuel oil into air at atmospheric pressure into a. heated chamber. The

ignition delay is the elapsed time between injection and ignition of the fuel. The minimum ignition temperature is the lowest temperature at which a majority of a series of samples injected into the chamber ignite. The minimum compression ratio was determined according to the method described by Pope and Murdock in the Society of Automotive Engineers Journal, Transactions, pages 136-142 for March 1932.

The compounds suitable for use according to examine the present invention all contain at least one ni- I trate group. The most generally satisfactory alkyl nitrates are those which contain at least two nitric ester groups. These nitrate esters are modified by the inclusion in their molecules of radi-' cals which confer upon them the property of dissolving to a substantial extent in fuel oil of the type used in Diesel engines. Examples .of solubilizing groups forming radicals in the said esters are halogen, aliphatic hydrocarbon, acyloxy, alkoxy and aryloxy radicals. In the case of the polynitrate esters, hydrocarbon radicals, both aliphatic and aromatic, increase the solubility of the compounds in the fuel oil. The compounds listed in the table described above are merely illustrative, the nitrate esters'being capable of considerable variation from the specific esters listed above. For purposes of simplicity the nitric esters of polyhydric alcohols which can be used in the practice of the present invention are divided into the following three general classes:

1. RHCa-(CHONOa) nH where n is 2 or more and R is hydrogen, or a hydrocarbon radical.

2. RCH2(CHONO2):H ,where a: may be any small whole number and R may be chosen from the class consisting of halogen, acyloxy, alkow, aryloxy, and a hydrocarbon radical containing a nitric ester group.

R OHaONO:

/O\ R1 CHaONOi where R may be a hydrocarbon radical and R1 may be chosen from groups consistingof hydro-' carbon, nitro, and nitric ester of methylol radi cals.

Specific examples of compounds of formula 1 comprise 1,2-propylene glycol dinitrate, 1,2- butylene glycol dinitrate, 1,2-amylene glycol dinitrate, and '3-phenyl-l,2-propylene glycol dini-- trate. v

Specific examples {of compounds of formula 2 comprise 1,3-butylene glycol dinitratambrioethyl ether of glycerol dinitrate (monoethylin dinitrate), monoacetic "acid ester of glycerol .di-

nitrate (monoacetin dinitrate), monophenyl ether of glycerol dinitrate, glycerylmonochloride dinitrate' (dinitro chlorhydrin),monoethyl ether of ethylene glycol nitrate.- ethylene chlorcause of knocking and roughness.

3. Easier starting. The reduced spontaneous ignition temperatures of the doped oil enable it to ignite much more easily when starting from cold.

4. Improved exhaust. Owing to the more complete combustion the exhaust is cleaner especially at higher speeds. No harmful constituents are introduced into the exhaust gases by the combustion of the dope.

5. Possibility of use of inferior fuels. By the addition of dope, low grade fuels, at present quite unsuitable for compression ignition engines, can be rendered equal or superior to high grade undoped fuels.

6. Nature of dope. The dope has a neutral reaction, is non-toxic and soluble in the oil.

7. Improvements in engine'design. Reduced engine stresses, resulting from the more gradually applied piston pressures, should make for lighter scantlings while the more readily ignited and rapidly burning fuel should render possible the construction of smaller and faster running engines.

8. Increased power and reduced fuel consumption. The improved combustion resulting from the explosive action of the dope enables a greater proportion of the air charge to be burnt, and further, as ignition takes place at once, the fuel can be injected during the compression stroke at a smaller crank angle near top dead center.

The advantages of the invention over the prior art result from decreased vapor pressure of the nitrates of modified polyhydric alcohols. boiling points of a few compounds used as fuel dopes, including those of the present invention, are given in the following table:

Dope Boiling point at mm. 0.

The,

Further advantages are:

1. The increased boiling point prevents the formation of vapor locks in the fuel system of the engine. a

2. Elimination of hazard in transportation and storage. The decreased vapor pressures eliminate the possibility of the formation of an explosive, dope-air mixture above the fuel in tank cars or storage tanks.

3. Decrease in objectionable physiological properties. The decreased vapor pressure of the dopes also decreases the physiological effects, such as headaches, which constitute an objection to lower alkyl nitrates.

The above description and examples are to be taken as illustrative only and not as limiting the scope of the invention. Any modification or variation therefrom which conforms to the spirit of the invention is intended to be included within the scope of the claims.

We claim:

1. A compression ignition engine fuel comprising a high boiling fuel 011 containing a nitrate of an aliphatic polyhydric alcohol selected from the group consisting of 1,2-propylene glycol dinitrate, 1,2-butylene glycol dinitrate, 1,2-amylene glycol dinitrate, 3-phenyl-1,2-propylene glycol dinitrate, 1,3-butylene glycol dinitrate, monoethyl ether of glycerol dinitrate, monoacetic acid ester of glycerol dinitrate, monophenyl ether of glycerol dinitrate, glyceryl monochloridedinitrate, monoethyl ethgr qgg t h ylene glycol 11 ethylene-chlorhydrin nitrate, ethylene bromhydrin nitrate, monophenyl ether of ethylene glycol nitrate, monoacetic acid ester of ethylene glycol nitrate, dimethyldimethylolmethane dinitrate, ethyltrimethylolmethane trinitrate, methyltrimethylolmethane trinitrate, and nitromethyldimethylolmethane dinitrate.

2. A compression ignition engine fuel comprising a high boiling fuel 011 containing monoethyl ether of glycerol dinitrate.

3. A compression ignition fuel comprising a high boiling fuel oil containing Lil-propylene glycol dinitrate.

4. A compression ignition fuel comprising a high boiling fuel oil containing dimethyldimethylolmethane dinitrate.

CLIFFORD A. WOODBURY. WAL'I'ER E. LAWSON.

Patent No. 2,066,506.

[snap] January 5, 1937.

CLIFFORD A. WOODBURY ET AL.

It is hereby certified that error appears in the numbered atent requiring correction as follows: for RHO, read RCH,; and that the said correction therein that the same may confo rinted specification of the above age 1, second column, line 32, Letters Patent should be read with this rm to the record of the case in the Patent Signed and sealed this 23rd day of March, A. D. 1637.

HENRY VAN ABSDALE, Ading Commissioner of Patents. 

